Catheter having multiple spines each having electrical mapping and location sensing capabilities

ABSTRACT

An improved catheter is provided that is particularly useful for mapping the electrical activity in a heart. The catheter comprises a plurality of spines each capable of obtaining electrical, mechanical and locational data. The catheter comprises an elongated catheter body having proximal and distal ends and at least one lumen extending longitudinally therethrough. Mounted at the distal end of the catheter body is a mapping assembly having at least two spines, each having a proximal end attached at the distal end of the catheter body and a free distal end. Each spine comprises at least one location sensor and at least one electrode, preferably a tip electrode and at least one ring electrode. The spines may be arranged in an expanded arrangement wherein each spine extends radially outwardly from the catheter body or in a collapsed arrangement wherein each spine is disposed generally along the longitudinal axis of the catheter body. In use, at least one electrode from each spine is positioned in contact with heart tissue to map the electrical activity of the heart. The location sensors are used to determine the location of each point where the electrical activity is monitored.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a divisional of U.S. patent application Ser.No. 10/040,932, filed on Dec. 31, 2001, now U.S. Pat. No. 6,961,602,entitled, “Catheter Having Multiple Spines Each Having ElectricalMapping And Location Sensing Capabilities.”

BACKGROUND OF THE INVENTION

Electrophysiology catheters are commonly used for mapping electricalactivity in a heart. Electrophysiology is a specialty within the fieldof cardiology for diagnosis and treatment of electrical abnormalities ofthe heart. By mapping the electrical activity in the heart, ectopicsites of electrical activation or other electrical activation pathwaysthat contribute to heart malfunctions may be detected. This type ofinformation may then allow a cardiologist to intervene and destroy themalfunctioning heart tissues. Such destruction of heart tissue isreferred to as ablation, which is a rapidly growing field withinelectrophysiology and obviates the need for maximally invasive openheart surgery.

Attached to the electrophysiology catheters are electrodes, which areused to map, or collect electrical information about, the electricalactivity in the heart. It is also known to incorporate into certainelectrophysiology catheters a location or position sensor fordetermining the location of the electrodes being used to map theelectrical activity in the heart. Such catheters are generally insertedpercutaneously and fed through one or more major blood vessels into achamber of the heart. A location sensor in the catheter, typically nearthe catheter's distal end, produces signals that are used to determinethe position of the device relative to a frame of reference, such as aposition external to the body or within the heart itself. The locationsensor may be active or passive and may operate by generating orreceiving electrical, magnetic or ultrasonic energy fields or othersuitable forms of energy known in the art.

U.S. Pat. No. 5,391,199, the disclosure of which is incorporated hereinby reference, describes a position-responsive catheter comprising aminiature sensor coil contained in the catheter's distal end. The coilgenerates electrical signals in response to externally-applied magneticfields, which are produced by field-generator coils placed outside thepatient's body. The electrical signals are analyzed to determine thethree-dimensional coordinates of the coil.

International Publication No. WO 96/05768, the disclosure of which isalso incorporated herein by reference, describes a position-responsivecatheter comprising a plurality of miniature, preferably non-concentric,sensor coils fixed in the catheter=s distal end. As in U.S. Pat. No.5,391,1999, electrical signals generated by these coils in response toan externally-applied magnetic field are analyzed so as to determine,for example, the six-dimensional coordinates of these coils, i.e. thepositional coordinates and the orientational coordinates.

Multiple position-sensing devices may be placed in a known,mutually-fixed spatial relation at or adjacent to the distal end of acatheter, as described, for example, in International Publication No. WO97/24983, the disclosure of which is incorporated herein by reference.This publication describes a catheter having a substantially rigidstructure at its distal end, to which one or more position sensors arefixed. The sensors are used to determine the position and orientation ofthe rigid structure.

SUMMARY OF THE INVENTION

The present invention is directed to an improved catheter for mappingthe electrical activity in a heart. The catheter comprises a pluralityof spines each capable of obtaining electrical, mechanical andlocational data.

In one embodiment, the invention is directed to a catheter comprising anelongated catheter body having proximal and distal ends and at least onelumen extending longitudinally therethrough. Mounted at the distal endof the catheter body is a mapping assembly having at least two spines,each having a proximal end attached at the distal end of the catheterbody and a free distal end. Each spine comprises at least one locationsensor and at least one electrode, preferably a tip electrode and atleast one ring electrode.

In a preferred embodiment, the invention is directed to a cathetercomprising an elongated catheter body having proximal and distal endsand at least one lumen longitudinally extending therethrough. Mounted atthe distal end of the catheter body is a mapping assembly having atleast two spines, each having a proximal end attached at the distal endof the catheter body and a free distal end. Each spine comprises atleast one location sensor, at least one electrode, and a non-conductivecovering having a support arm that has shape memory. Preferably, eachspine comprises a tip electrode and at least one ring electrode. Themapping assembly is moveable between an expanded arrangement, in whicheach spine extends radially outward from the catheter body and acollapsed arrangement, in which each spine is disposed generally along alongitudinal axis of the catheter body. In use, at least one electrodefrom each spine may be positioned in contact with heart tissue to mapthe electrical activity of the heart. The location sensors may be usedto determine the location of the electrodes at each instance when theelectrodes are obtaining electrical activity data.

DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a catheter according to the invention.

FIG. 2 is a side cross-sectional schematic view of a portion of thecatheter of FIG. 1, taken from line 2—2 in FIG. 1.

FIG. 3 is an end cross-sectional view of a portion of the catheter ofFIG. 1, taken from line 3—3 in FIG. 2.

FIG. 4 is a side cross-sectional schematic view of one of the spines ofthe catheter of FIG. 1, taken from line 4—4 in FIG. 1.

FIG. 5 is an end cross-sectional view of the tip electrode of the spineof FIG. 4, taken from line 5—5 in FIG. 4.

FIG. 6 is a perspective view of a pigtail dilator useful forintroduction of the catheter of FIG. 1 into a patient.

FIG. 7 is a perspective view of an alternative embodiment of an expandedarrangement of the mapping assembly of a catheter according to theinvention.

FIG. 8 is a perspective view of another alternative embodiment of anexpanded arrangement of the mapping assembly of a catheter according tothe invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to a catheter having a mapping assemblycomprising a plurality of spines. Each spine carries at least onelocation sensor and at least one electrode, preferably a tip electrodeand at least one ring electrode, such that when the spines arepositioned in contact with heart tissue, each spine is capable ofobtaining electrical, mechanical and locational data. As shown in FIG.1, the catheter 10 comprises an elongated catheter body 12 havingproximal and distal ends, a control handle 16 at the proximal end of thecatheter body 12, and a mapping assembly 18 comprising a plurality ofspines 14 mounted at the distal end of the catheter body 12.

As shown in FIGS. 1 and 2, the catheter body 12 comprises an elongatedtubular construction having a single, axial or central lumen 15, but canoptionally have multiple lumens along all or part of its length ifdesired. The catheter body 12 is flexible, i.e., bendable, butsubstantially non-compressible along its length. The catheter body 12can be of any suitable construction and made of any suitable material. Apresently preferred construction of the catheter body 12 comprises anouter wall 13 made of polyurethane or PEBAX® (polyether block amide).The outer wall 13 comprises an imbedded braided mesh of stainless steelor the like, as is generally known in the art, to increase torsionalstiffness of the catheter body 12 so that, when the control handle 16 isrotated, the distal end of the catheter body 12 will rotate in acorresponding manner.

The length of the catheter body 12 is not critical, but preferablyranges from about 90 cm to about 120 cm, and more preferably is about110 cm. The outer diameter of the catheter body 12 is also not critical,but is preferably no more than about 8 french, more preferably about 7french. Likewise, the thickness of the outer wall 13 is not critical,but is preferably thin enough so that the central lumen 15 canaccommodate puller wires, lead wires, sensor cables and any other wires,cables or tubes. If desired, the inner surface of the outer wall 13 islined with a stiffening tube (not shown) to provide improved torsionalstability. An example of a catheter body construction suitable for usein connection with the present invention is described and depicted inU.S. Pat. No. 6,064,905, the entire disclosure of which is incorporatedherein by reference.

In the depicted embodiment, the mapping assembly 18 comprises fivespines 14. Each spine 14 has a proximal end attached at the distal endof the catheter body 12 and a free distal end, i.e., the distal end isnot attached to any of the other spines, to the catheter body, or to anyother structure that confines movement of the distal end. Each spine 14contains a support arm 24 comprising a metal or plastic material thathas shape memory, such that the support arm 24 forms an initial shapewhen no external forces are applied, forms a deflected shape when anexternal force is applied, and returns to its initial shape when theexternal force is released. In a preferred embodiment, the support arm24 comprises a superelastic material, for example a nickel-titaniumalloy, such as Nitinol. Each spine 14 also comprises a non-conductivecovering 26 in surrounding relation to the support arm 24. In apreferred embodiment, the non-conductive covering 26 comprises abiocompatible plastic tubing, such as a polyurethane or polyimidetubing.

As will be recognized by one skilled in the art, the number of spines 14can vary as desired depending on the particular application, so that thecatheter 10 has at least two spines, preferably at least three spines,more preferably at least five spines and as many as eight or morespines. As described in more detail below, the spines 14 are moveablebetween an expanded arrangement, wherein, for example, each spineextends radially outwardly from the catheter body 12, or the spines 14may be arranged in a collapsed arrangement, wherein, for example, eachspine is disposed generally along a longitudinal axis of the catheterbody 12 so that the spines are capable of fitting within a lumen of aguiding sheath, as discussed further below.

Each spine 14 carries at least one electrode mounted along its length,preferably at or near its distal end. In the depicted embodiment, a tipelectrode 20 is mounted on a distal end of each non-conductive covering26 and at least one ring electrode 28 is mounted on each non-conductivecovering 26, preferably on the distal end of the non-conductive covering26. In this bipolar arrangement, the ring electrode 28 is used as areference electrode. The distance between the tip electrode and ringelectrode preferably ranges from about 0.5 mm to about 2 mm. In analternative bipolar arrangement (not shown), the tip electrode 20 iseliminated and at least two ring electrodes 28 are mounted on eachnon-conductive covering 26, preferably on the distal end of thenon-conductive covering 26. Another alternative embodiment (not shown),is a unipolar arrangement, in which the tip electrode 20 is mounted onthe distal end of each non-conductive covering 26, with one or morereference ring electrodes mounted on the distal end of the catheter body12, or one or more reference electrodes attached outside the body of thepatient (e.g., in the form of a patch). In an alternative unipolararrangement, a ring electrode 28 mounted on each non-conductive covering26, preferably on the distal end of the non-conductive covering 26, isused instead of a tip electrode 20.

Each tip electrode 20 has an exposed length preferably ranging fromabout 0.5 mm to about 4 mm, more preferably from about 0.5 mm to about 2mm, still more preferably about 1 mm. Each ring electrode 28 has alength preferably up to about 2 mm, more preferably from about 0.5 mm toabout 1 mm.

Each tip electrode 20 and each ring electrode 28 is electricallyconnected to an electrode lead wire 29, which in turn is electricallyconnected to a connector 17. The connector 17 is connected to anappropriate mapping or monitoring system (not shown). Each electrodelead wire 29 extends from the connector 17, through the control handle16, through the central lumen 15 in the catheter body 12, and into thenon-conductive covering 26 of the spine 14 where it is attached to itscorresponding tip electrode 20 or ring electrode 28. Each lead wire 29,which includes a non-conductive coating over almost all of its length,is attached to its corresponding tip electrode 20 or ring electrode 28by any suitable method.

A preferred method for attaching a lead wire 29 to a ring electrode 28involves first making a small hole through an outer wall of thenon-conductive covering 26. Such a hole can be created, for example, byinserting a needle through the non-conductive covering 26 and heatingthe needle sufficiently to form a permanent hole. The lead wire 29 isthen drawn through the hole by using a microhook or the like. The end ofthe lead wire 29 is then stripped of any coating and welded to theunderside of the ring electrode 28, which is then slid into positionover the hole and fixed in place with polyurethane glue or the like.Alternatively, each ring electrode 28 may be formed by wrapping the leadwire 29 around the non-conductive covering 26 a number of times andstripping the lead wire of its own non-conductive coating on itsoutwardly facing surfaces. In such an instance, the lead wire 29functions as a ring electrode.

Each spine 14 also includes at least one location sensor 30. Thelocation sensor 30 is mounted near the distal end of each spine. In thedepicted embodiment, where each spine 14 comprises a tip electrode 20, alocation sensor 30 is mounted such that the distal end of the locationsensor 30 is secured within its corresponding tip electrode 20, whilethe proximate end of the location sensor 30 extends into the distal endof the non-conductive covering 26. Each location sensor 30 is used todetermine the coordinates of its corresponding tip electrode 20 at eachinstant when the tip electrode 20 is being used to collect an electricalmapping data point. As a result, both electrical and locational data canbe obtained for each data point that is mapped. If the spine 14 carriesat least one ring electrode 28 but does not include a tip electrode 20,the location sensor 30 is mounted near the distal end of thenon-conductive covering 26, preferably as close to the distal end of thespine 14 as possible or in a plane concentric with the ring electrode28.

Each location sensor 30 is connected to a corresponding sensor cable 36.Each sensor cable 36 extends through the non-conductive covering 26,catheter body 12 and control handle 16 and out the proximal end of thecontrol handle 16 within an umbilical cord (not shown) to a sensorcontrol module (not shown) that houses a circuit board (not shown).Alternatively, the circuit board can be housed within the control handle16, for example, as described in U.S. Pat. No. 6,024,739, the disclosureof which is incorporated herein by reference. Each sensor cable 36comprises multiple wires encased within a plastic covered sheath. In thesensor control module, the wires of the sensor cable 36 are connected tothe circuit board. The circuit board amplifies the signal received fromthe corresponding location sensor 30 and transmits it to a computer in aform understandable by the computer by means of a sensor connector atthe proximal end of the sensor control module. Also, because thecatheter 10 is designed for single use only, the circuit boardpreferably contains an EPROM chip that shuts down the circuit boardapproximately twenty-four hours after the catheter 10 has been used.This prevents the catheter 10, or at least the location sensors 30, frombeing used twice.

Preferably each location sensor 30 is an electromagnetic locationsensor. For example, each location sensor 30 may comprise amagnetic-field-responsive coil, as described in U.S. Pat. No. 5,391,199,or a plurality of such coils, as described in International PublicationWO 96/05758. The plurality of coils enables the six-dimensionalcoordinates (i.e. the three positional and the three orientationalcoordinates) of the location sensor 30 to be determined. Alternatively,any suitable location sensor known in the art may be used, such aselectrical, magnetic or acoustic sensors. Suitable location sensors foruse with the present invention are also described, for example, in U.S.Pat. Nos. 5,558,091, 5,443,489, 5,480,422, 5,546,951, and 5,568,809, andInternational Publication Nos. WO 95/02995, WO 97/24983, and WO98/29033, the disclosures of which are incorporated herein by reference.A particularly preferred location sensor 30 is a single axis sensorhaving a length ranging from about 3 mm to about 7 mm, preferably about4 mm, such as that described in the U.S. patent application Ser. No.09/882,125 filed Jun. 15, 2001, entitled “Position Sensor Having Corewith High Permeability Material,” the disclosure of which isincorporated herein by reference. Smaller sensors are particularlydesirable for use in the present invention because of the need to keepthe diameters of the spines 14 small enough so that they all fit withinthe lumen of a guiding sheath.

FIGS. 4 and 5 illustrate a suitable technique for mounting the electrodelead wire 29, the location sensor 30 and the support arm 24 to the tipelectrode 20. The electrode lead wire 29 may be secured to the tipelectrode 20 by drilling a first blind hole 48, preferably a bore hole,into the tip electrode 20, stripping the lead wire 29 of any coating andplacing the lead wire 29 within the first blind hole 48 where it iselectrically connected to the tip electrode 20 by a suitable means, suchas by soldering or welding. The lead wire 29 may then be fixed in place,for example, by using a polyurethane glue or the like. The locationsensor 30 may be similarly affixed to the tip electrode 20. For example,a second blind hole 50, preferably a bore hole, may be drilled into thetip electrode 20 such that the location sensor 30 may be inserted intothe second blind hole 50 and affixed therein, for example, using apolyurethane glue or the like. The support arm 24 may also be similarlyaffixed to the tip electrode 20. For example, a third blind hole 52,preferably a bore hole, may be drilled into the tip electrode 20 suchthat the support arm 24 may be inserted into the third blind hole 52 andaffixed therein, for example, using a polyurethane glue or the like.Alternatively, a single blind hole (not shown) in the proximal end ofthe tip electrode 20 can be used for mounting the location sensor 30 andsupport arm 24, and the distal end of the lead wire 29 can be wrappedaround the outside proximal end of the tip electrode, which is notexposed and attached by solder, welding or any other suitable technique.Any other arrangement for mounting these components in the spine couldalso be used.

A suitable construction of the distal end of the catheter body 12,having spines 14 mounted thereto, is depicted in FIGS. 2 and 3. Forclarity, only two spines 14 are shown in FIG. 2. Mounted in the distalend of the lumen 15 of the catheter body 12 is a spine mounting assembly31. The spine mounting assembly 31 comprises an outer mounting ring 32disposed within the outer wall 13 of the catheter body 12. The outermounting ring 32 preferably comprises a metal material, such asstainless steel, more particularly stainless steel 303, and may beattached at the distal end of the catheter body 12 by a variety ofmethods, such as by welding or by use of an adhesive, such as apolyurethane glue. Alternatively, the outer mounting ring 32 maycomprise a plastic material. A mounting structure 34 is providedcoaxially within the outer mounting ring 32. In the depicted embodiment,the mounting structure 34 is multi-sided and comprises a metal material,such as stainless steel, more particularly stainless steel 303. Themounting structure 34 may also alternatively comprise a plasticmaterial. The outer mounting ring 32 and the mounting structure 34provide a channel 38 in which the proximal end of each support arm 24 ismounted. Specifically, each spine 14 is mounted in the catheter body 12by removing a portion of the non-conductive covering 26 at the proximalend of each spine 14, inserting the distal end of each support arm 24into the channel 38 between the outer mounting ring 32 and themulti-sided mounting structure 34 and affixing each support arm 24within the channel 38 by any suitable means, such as with a polyurethaneglue or the like.

In a preferred embodiment, the support arm 24 has a generallytrapezoidally-shaped end cross section with curved sides. In such anarrangement, when each support arm 24 is inserted into the channel 38, asubstantially flat surface of each support arm 24, preferably the baseof the trapezoidally-shaped end cross section, is mounted against asubstantially flat surface on the multi-sided mounting structure 34.Preferably the number of substantially flat outer surfaces on themulti-sided mounting structure 34 corresponds to the number of spines14. In such an instance, the support arm 24 of each spine 14 may bemounted within the channel 38 and adjacent to its corresponding side onthe multi-sided mounting structure 34 to enable the support arms 24, andthus the spines 14, to be equally spaced around the multi-sided mountingstructure 34. The multi-sided mounting structure 34 may be approximatelyco-axial with the longitudinal axis of the catheter body 12 such thatthe spines 14 are equally spaced about the catheter body 12 as well.Once each support arm 24 is properly positioned within the channel 38,each support arm 24 may be affixed within the channel 38 by any suitablemeans, such as by use of an adhesive, such as a polyurethane glue.Alternatively, the mounting structure 34 can have a round outer surface,although with such an embodiment more care needs to be taken if thesupport arms 24 are to be evenly spaced about the mounting structure.

In the depicted embodiment, a first non-conducting tube 40 is disposedbetween the outer mounting ring 32 and the support arms 24, and a secondnon-conducting tube 42 is disposed between the support arms 24 and themounting structure 34. The non-conducting tubes 40 and 42, which may bepolyimide tubes, ensure that each support arm 24 remains electricallyisolated. In addition, a mounting ring inner tube 44 is secured withinthe mounting structure 34. The mounting ring inner tube 44 preferablycomprises a non-conducting material such as polyimide. The mounting ringinner tube 44 defines a mounting ring lumen 46 through which each of theelectrode lead wires 29 and sensor cables 36 extend.

As previously discussed, when mounting the support arms 24 to the spinemounting assembly 31, a portion of the non-conductive covering 26 at theproximal end of each spine 14 is removed to expose the support arm 24.Removing a portion of the non-conductive covering 26 at the proximal endof each spine 14 enables the electrode lead wires 29 and sensor cables36, corresponding to each tip electrode 20, ring electrode 28 andlocation sensor 30, to extend from the lumen 15 of the catheter 12,through the mounting ring lumen 46, and into each non-conductivecovering 26. As shown in FIG. 4, once inserted into the non-conductivecoverings 26, the electrode lead wires 29 and sensor cables 36 extendwithin the non-conductive covering 26 and are electrically connected attheir distal ends to their corresponding tip electrode 20, ringelectrode 28 or location sensor 30.

To use the catheter 10 of the invention, a cardiologist orelectrophysiologist introduces a guiding sheath and a dilator into thepatient, as is generally known in the art, so that the distal ends ofthe sheath and dilator are in the region of the heart to be mapped. Insome instances, such as when it is desired to insert the catheter 10into the left ventricle through the aortic valve in a direction oppositethe blood flow, it is preferable to use a pigtail-shaped dilator 54having a distal end 56 that forms a loop 58, as shown in FIG. 6.Specifically, the side of the loop 58 is pushed against the flaps of thevalve and serves essentially as a blunt instrument to push the flapsinward so that they are temporarily inverted while the dilator andguiding sheath are advanced through the valve. By using the surface ofthe loop 58 to push the flaps of the valve, potential puncturing of theflaps of the valve can be avoided. In contrast, pushing the flaps with adilator having a straight distal end can potentially puncture orotherwise damage the flaps. After the dilator and guiding sheath havingbeen advanced through the valve with the loop 58 inside the leftventricle, the flaps of the aortic valve return to their original,natural position.

Thereafter, the dilator is removed from the guiding sheath, and thecatheter 10 is introduced into the patient through the guiding sheath.To insert the catheter 10 into the guiding sheath, the mapping assembly18 must be in its collapsed arrangement, wherein each spine 14 isdisposed generally along the longitudinal axis of the catheter body 12.A suitable guiding sheath for use in connection with the catheter 10 isthe PREFACE™ Braided Guiding Sheath (commercially available fromBiosense Webster, Inc., Diamond Bar, Calif.). Such a guiding sheath hassufficient strength to hold each support arm 24 in the collapsedarrangement, such that the spines 14 and also the entire remainder ofthe catheter 10 can travel within the guiding sheath, from an insertionpoint in the patient, through a vein or artery and to a desired locationin the heart. Once the distal end of the catheter has reached thedesired location, such as a position within the left ventricle of theheart, relative longitudinal movement between the catheter 10 and theguiding sheath is provided to allow at least a portion of each spine 14to protrude from the guiding sheath. Preferably the guiding sheath ismoved proximally relative to the distal end of the catheter to exposethe spines 14. When a portion of each spine 14 protrudes from theguiding sheath and a compression force is no longer applied by theguiding sheath on the spines, the shape memory of the support arms 24allows the support arms to revert to a first expanded arrangement. Inthe first expanded arrangement, at least one electrode from each spine14 can be placed into contact with a first plurality of the heart tissuesuch that electrical, locational and mechanical information can beobtained from the contacted heart tissue. The spines 14 can then berepositioned to a second expanded arrangement to contact a secondplurality of heart tissue such that electrical, locational andmechanical information can be obtained from these tissues as well. Thisrepositioning is preferably achieved by further moving the guidingsheath proximally relative to the catheter to thereby expose a greaterportion of each spine. In the depicted embodiment, the more of eachspine that is exposed, the further each spine can bend or expand awayfrom the catheter to thereby contact heart tissue. This process can berepeated until the heart has been satisfactorily mapped.

The expanded arrangement of spines 14 can take on various shapes. Forinstance, in the above-described embodiment, each spine 14 extendsradially outwardly from the catheter body 12 and forms an outwardlycurved shape as shown in FIG. 1. In another embodiment, shown in FIG. 8,each spine 14 extends radially outwardly from the catheter body 12 andforms a substantially straight line, which is preferably substantiallyperpendicular to the catheter body 12. In still another embodiment,shown in FIG. 7, each spine 14 bows radially outwardly such that thespines 14, taken together, form a cup shape.

Using the inventive catheter 10 having multiple spines 14, each havingelectrical and mechanical mapping and locational sensing capabilities,the cardiologist can map local activation time and obtain voltage maps.The cardiologist can also determine those locations in the heart havingno mechanical activity by monitoring whether the position of thelocation sensor changes over a complete cardiac cycle. This informationcan guide the cardiologist in providing therapy to the patient. Forexample, where the cardiologist finds regions of the heart that do nothave mechanical activity, he or she can revascularize those regionsusing known techniques, such as gene therapy or transmyocardialrevasularization. The inventive catheter 10 allows the cardiologist tomap the heart more quickly than traditional catheters by measuringmultiple points of data at a time.

If desired, the catheter may include a steering mechanism for deflectionof the distal end of the catheter body 12. With such a design, thedistal end of the catheter body 12 preferably comprises a short lengthof tubing, e.g., 2 to 4 inches in length, that is more flexible than theremainder of the catheter body 12. A suitable steering mechanismcomprises a puller wire (not shown) that extends from a proximal end inthe control handle 16, through the central lumen 15 in the catheter body12 and into an off axis lumen in the short length of tubing. Within thecatheter body 12, the puller wire extends through a closely wound coilthat is bendable but substantially non-compressible. The coil is fixednear the proximal and distal ends of the catheter body 12 and preventsdeflection of the catheter body 12. The distal end of the puller wire isanchored at the distal end of the short length of tubing in the off axislumen. The proximal end of the puller wire is anchored to a movablemember in the handle 16 that can be moved relative to the catheter body12. Proximal movement of the movable member relative to the catheterbody 12 results in deflection of the short length of tubing. An exampleof such a steering mechanism and construction is described in moredetail in U.S. Pat. No. 6,064,905, the disclosure of which isincorporated herein by reference. When incorporating a steeringmechanism into the inventive catheter 10, it may be desirable to includea location sensor at the distal end of the catheter body 12. As would berecognized by one skilled in the art, of a slurring mechanism is notincluding, the handle 16 can be eliminated, although it is described tomaintain the handle for ease of use by the cardiologist.

The preceding description has been presented with references topresently preferred embodiments of the invention. Persons skilled in theart and technology to which this invention pertains will appreciate thatalterations and changes in the described structures can be practicedwithout meaningfully departing from the principle, spirit and scope ofthis invention. Accordingly, the foregoing description should not beread as pertaining only to the precise structures described and shown inthe accompanying drawings, but rather should be read as consistent withand as support for the following claims, which are to have their fullestand fairest scope.

1. A catheter comprising: an elongated catheter body having a proximalend, a distal end and at least one lumen extending longitudinallytherethrough; and a mapping assembly mounted at the distal end of thecatheter body and comprising at least two spines, each spine having aproximal end attached at the distal end of the catheter body and a freedistal end, wherein each spine comprises: a support arm having shapememory; a non-conductive covering in surrounding relation to the supportarm; at least one location sensor mounted at or near the distal end ofthe spine; a tip electrode mounted at or near the distal end of thespine and electrically isolated from the support arm; at least one ringelectrode mounted in surrounding relation to the non-conductivecovering; and a plurality of electrode lead wires extending within thenon-conductive covering, each electrode lead wire being attached to acorresponding one of the tip electrode and ring electrode.
 2. Thecatheter of claim 1, wherein each support arm comprises nitinol.
 3. Thecatheter of claim 1, wherein the mapping assembly is moveable between anexpanded arrangement, in which each spine extends radially outward fromthe catheter body, and a collapsed arrangement, in which each spine isdisposed generally along a longitudinal axis of the catheter body. 4.The catheter of claim 3, wherein, when the mapping assembly is in itsexpanded arrangement, each spine extends radially outwardly from thecatheter body and forms a curved shape.
 5. The catheter of claim 3,wherein, when the mapping assembly is in its expanded arrangement, eachspine extends radially outwardly from the catheter body and forms asubstantially straight line.